The Casimir effect is a known effect in physics, in which an attraction or repulsion exists between closely spaced objects. The Casimir effect is believed to be quantum mechanical in nature, as explained at Wolfram Scienceworld (Casimir Effect) (http://scienceworld.wolfram.com/physics/CasimirEffect.html), and in New Developments in the Casimir Effect, M. Bordag, U. Mohideen, and V. M. Mostepanenko, Elsevier Preprint (November 2005). This interpretation is disputed by some, cf., The Casimir Effect and the Quantum Vacuum, R. Jaffe, Phys. Rev. D72 (2005). While the Casimir effect has little effect on objects at human-scale, it has been precisely measured and is assuredly real.
Attempts have been made to convert or to extract energy using movement of closely spaced parallel plates together as a result of the Casimir effect. However, as much energy is needed to reset the plates by pulling the plates apart as can be extracted from movement of the plates together. Therefore, no net energy has been converted or extracted in these prior-art attempts.